With the blower running non stop it means that the stove is putting out heat faster than the blower can remove it. The fan/limit control is set to turn on the fan when the heat in the plenum reaches whatever temperature the control is set at and to turn off the fan when the temperature falls below that setting to avoid blowing cold air. There is a differential which you can set. The limit part does not function since the furnace is manually controlled. There is usually a switch to turn on the blower manually which I assume you are not using, but letting the blower run automatically controlled by the fan control.jschaefer7406 wrote:This uses a heat exchanger and convection blower to send the heat through the ductwork into the house. Blower is running non-stop, but I imagine that's normal with a standard mechanical fan/limit control. Hope that answers your question
Anything you can do to make the blower more efficient in removing the heat from the furnace will lower stack temperature and put more of the heat into the house. How is the cool air from the house getting back to the furnace? One picture shows what looks like a return at the base of the coal furnace. The size of a return should be at least the size of the feed duct. It really should be connected to the return duct for the house. Failing that, the existing return to the oil furnace should have an opening so that the coal furnace can pull the cold air from the house.
How warm is the basement? You could be losing a lot of heat there. Another picture from further away showing the complete coal furnace and piping would help. Don't forget to oil the blower motor and fan bearings if so equipped.